Is Cardio Necessary for Fat Loss when Intermittent Fasting?

Cardio as a tool for fat loss is over-rated, over-used, and overall a very poor time investment for the IF user.

“Time is your most precious gift because you only have a set amount of it. You can make more money, but you can’t make more time. When you give someone your time, you are giving them a portion of your life that you’ll never get back.”

I don’t have a problem with cardio, just wasted time. For those that enjoy cardio then this is time well spent; everyone has their own preferences, live and let live. Let’s not pretend though that most people aren’t solely doing cardio because they wish to lose fat.

Cardio as a tool for fat loss is over-rated, over-used, and overall a very poor time investment for the IF user. Most people that ask me questions about cardio understand this, however there is confusion as to at what point cardio becomes necessary to get leaner.

In my opinion the vast majority of people give up on diet manipulation alone as a means of achieving their ideal physique way too early.

At What Point Do You Need Cardio?

Intermittent Fasting (particularly the Leangains type where people skip breakfast) can perhaps enable us to get to leaner than with other diet methods through diet manipulation alone. This is due to the following factors:

The increased ease at creating a calorie deficit through an increase in satiety and better hunger control.

The increased potential to get to stubborn fat.

This article focuses on the latter point, though I must add that it is hypothetical, with little clinical research to support it at present. This will be enough for most people, however, there is a limit to how far you can take it no matter how skillful you are at manipulating your diet; the reason is stubborn body fat.

What Is Stubborn Body Fat?

Stubborn body fat is physiologically different from other fat in your body and this makes the removal of it difficult. Typically stubborn fat is found in the lower abs, back, and glutes in men; thighs, glutes, and hips in women.

What Makes Stubborn Fat Stubborn?

There is a theoretical limit on how much fat can be oxidized (burned) before the body will fuel itself by breaking down muscle mass. Fatter individuals can afford a greater deficit before this happens than leaner individuals because the body uses fuels in the ratio they are available. – Fat people clearly have their pantry stocked with a lot of butter, a little meat; shredded people with just a little butter, a lot of meat.

For fat loss three things need to happen:

Lipolysis: Fat needs to be broken down into free fatty acids (FFAs) and released from the fat cell into the blood stream.

Transport: The FFAs need to be transported through the blood to somewhere where they can be used for fuel.

Oxidation: Tissues somewhere in the body need to pluck these FFAs from the blood stream and use them for energy.

When getting really lean (assuming a calorie deficit) the body has only muscle or the stubborn fat reserves left to fuel itself on. Due to the physiological differences of stubborn fat, both 1 and 2 are particularly tough to achieve. So though a calorie deficit may be present and the body ready to use the free fatty acids as energy (step 3), if they aren’t in the blood stream around those tissues, they can’t be used, and the body will break down muscle tissue to fuel itself. Clearly, you want to avoid this situation.

Unfavourable (for physique purposes) alpha/beta receptor ratio differences in the stubborn fat areas of the body are what makes it difficult for lipolysis to take place. To keep it simple, let’s just say that the morning fasting, by increasing catecholamine output and lowering insulin in the blood stream, creates circumstances which help to get around the receptor issues to allow the fat to escape the fat cells.

How Cardio Helps With Transport (by getting more blood flow to the right areas)

Before your eyes glaze over with the science please stand up and drop your pants. Take your right palm and slide it onto your right arse cheek. Is it cold? Relatively colder I bet. That’s because the blood flow to your glutes and other stubborn-fat areas is poorer. This matters because even if you overcome the problems associated releasing the FFAs (fat) into the blood stream if there isn’t sufficient enough blood flow to carry them elsewhere to be burned then they will just be reabsorbed into the fat cell.

Cardio can increase blood flow to these areas, which is one reason why you may have heard nutritionist Martin Berkhan recommend fasted walking on non-training days.

Yohimbine HCL can increase blood flow to these areas, which is why you may have heard that recommended also, but it would be a waste of money to take it before you get to the stubborn fat stage. (Incidentally it’s banned in many countries, not because of people taking it for stubborn fat loss, but because of idiots mega-dosing with it to boost erections.)

The Risks: IF can make it easier to burn stubborn fat, but increases the risk of muscle loss.

It would be remiss of me to not mention this: The leaner we get, the greater the potential for muscle loss with a reduced meal frequency. It’s important to put this in perspective and weigh up the pros and cons.

If you eat a greater meal frequency and spread your meals further across the day instead of skipping breakfast, your risk of muscle mass losses will be minimized, but you add in more complication to your diet. – Meal preparation takes more time, macro counting is incrementally harder, and you likely have to add in cardio sooner to get shredded lean. (i.e. If you skip breakfast you might be able to get to 7% body fat without cardio, but if you eat breakfast you might only be able to get to 9%.)

How much of a risk is it to skip breakfast?

This depends. The greater the calorie deficit and the leaner you are, the greater the risk of muscle loss. But if you take things slow and steady then the risk is small. I’ve coached over 1000 people with the majority of them choosing to skip breakfast and I can’t say I have noticed it causing any significant lean tissue losses. The clients you see in the top picture skipped breakfast, ate twice a day, and did not use any cardio to get into that condition.

However, it’s important to consider that they were recreational trainees without a deadline, not professional or serious amateur competitors looking to get any potential possible edge over the competition. The calorie deficits were moderate, training intensity was kept high, protein intake was kept high, and BCAAs were used in cases where they trained fasted. (My guide to setting this all up here.) In the case of a top-tier bodybuilder, it would be better to go with the more conservative approach and have a higher meal frequency (assuming they had the time and will to do it). Also, if someone is in a rush to get into stage-ready condition and so the deficit they need to have is greater than what would be most conservative for muscle mass retention, a greater meal frequency should be considered.

I’d add further that anyone convinced that they will lose muscle mass by fasting would be best to not fast. – The mind has a powerful effect on the body and this could indirectly cause muscle mass losses via increased stress and poorer training.

What if muscle mass is lost?

Outside of competing, it won’t really matter as you’ll gain it all back again quickly when you move into maintenance calorie circumstances after your cut. This isdue to good old myonuclear domain theory.

Summary & Further Reading

Don’t kid yourself about what stubborn body fat is. Too often people at 15% cry about “stubborn body fat” when they are nowhere near that point yet. Due to genetic difference some folks seem to have more stubborn fat than others. If we say that the above three guys are at around 7%, even if you’re on the unlucky end of that genetic difference you should be able to get to 10% before running into issues. This will still be good enough for a good set of abs, at the very least a well-defined 4 pack.